So this is the one I showed how to make the walls. I added some wooden stems. Would also perfectly work as trench...
Here I also added some wooden stems onto the floor to create some different look to the standard stone tiles.
Here I just added some metal grid and another look on ethe stone tiles.
Another tile with some industrial tanks and pipelines. Also added several pieces of plastcard on the floor.
On this last piece I actually didn't do much. Just added a piece of plastcard as floor tile and some carboard on the walls.
Well that's it for today. Next step will be finishing the industrial tile and adding some more details to the walls and floors.